Effect of organic sulfur-containing compounds on thermal oxidation stability of jet fuel

Thermal oxidation stability of jet fuel is an important issue when the fuel serves as the coolant for the overheating components of aircraft, and this stability can be significantly deteriorated by sulfur-containing compounds (SCCs). However, the effect of SCCs on fuel oxidation dynamics and mechanism remain unclear. In this work, we investigated the effect of SCC type on the thermal oxidation stability of the model fuel decalin using the PetroOxy device. The results show that the organic SCCs including thiols, alkyl sulfides, disulfides and benzothiophene would promote the deposition tendency, while the aromatic sulfides, thiophene and dibenzothiophene exhibit negligible impacts on deposition process. The deposition propensity of different SCCs relies on their ability to transfer polar products into deposition. GC × GC characterizations confirm that S-phenyl benzenesulfonothioate (S-PBTS) is the key intermediate in the deposition process of diphenyl disulfide. The dynamic calculation shows that the activation energy of oxidation is enhanced by hexane thiol and reduced by diphenyl disulfide. This mainly depends on the different reaction paths of the thiol and the disulfide. This work may provide guidance for recognizing the SCCs that are harmful to jet fuel thermal oxidation stability.